Stitching machine improvements

ABSTRACT

After a curved needle is passed through work material a first gripper grip holds the seam side loop of thread to prevent the pull of a looper on the other loop of thread from being transmitted back into the formed stitch. The first gripper doesn&#39;&#39;t release until after a second gripper near a thread puller to which the looper transfers the other loop grips the other loop.

United States Patent 11 1 Mills, Jr. 1451 Sept. 11, 1973 STITCHING MACHINE IMPROVEMENTS 2.368.066 1 1945 Johnson 112/171 [75] Inventor: James C. Mills, Jr.,Richmond,Va.

7 Primary ExaminerH. Hampton Hunter [73] Assignee: AMF Incorporated, White Plains, Attorney-George W. Price and Walter Lewis [22] Filed: Oct. 9, 1968 57] ABSTRACT [21] Appl' 766044 After a curved needle is passed through work material a first gripper grip holds the seam side loop of thread 52 US. (:1. 112/170 to prevent the p of e leeper on the ether p of [51] Int. Cl D0511 23/00 thread from being transmitted back into the formed [581' Field of Search 112/170, 171, 172, Stitch The first pp deesnt release until after asee- 112/176, 177, 173, 226 0nd gripper near a thread puller to which the looper transfers the other loop grips the other loop.

[56] References Cited NITE STATES PATENTS 117,986" 12/1877 Crosby 112 170 1 Claim, 8 Drawing Figures PATENTED SEPI 1 IQYB mm m w a FIG. 2

PATENTEDSEPI NW5 757, 7 1 3 SHEET t UP 4 STITCIIING MACHINE IMPROVEMENTS This invention relates to stitching machine improve ments, and more particularly, to improvements in the stitching machine described and claimed in copending John E. Hinckle United States patent application Ser. No. 666.035 filed Sept. 7, 1967 now U.S. Pat. No. 3,526,197, dated Sept. 1, 1970, for Stitching Machine and assigned to the same assignee as the instant patent application.

Briefly, said I-linckle copending patent application discloses a blind fell stitching machine comprising two opposed oscillatory needle chucks and a curved needle transferred back and forth between the two chucks during stitching. The rear one of said chucks passes the neddle through a node or hump of the material or work to be stitched and into the front chuck. The front chuck receives the needle from the rear chuck and continues to move the curved needle through the work until it passes entirely therethrough. After this, the front chuck backs up slightly to slacken the near and far loops or lates hand stitching in that a threaded needle is first passed entirely through the work, then the loose end of the thread is drawn entirely through the work, and thereafter the threaded needle is returned to proper position near the work for the next stitch. Of course, in hand stitching the thread is pulled entirely through the work by simultaneously moving the needle clear away from thework. In the stitching machine the equivalent is accomplished by holding the needle stationary inthe front chuck after it has cleared the work and pulling just the loose thread end clear through and away from the work by the looper and thread puller. Otherwise, the sequence of operations is the same as in hand stitching and gives a similar end product in terms of looks and quality.

In the above described machine a thread gripper is provided to grasp and hold one side of the enlarged near loop of thread so that the pull of the thread puller on the trailingend of the thread is not transmitted back into the stitch to cause puckering at the stitched seam. However, this gripper does not prevent the tension or pull of the looper on the thread from being transmitted back into the stitch or seam.

Therefore, it is an object of this invention to prevent the pull or tension of the looper on the near loop from being transmitted back into the stitch orseam.

Briefly, I have discovered that the employment of a properly sequenced thread gripper at the far loop to hold it will prevent the pull or tension of the looper on the near loop from being transmitted into the stitch o a seam.

The features of the invention which are believed to be novel are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a partial front view of the I-Iinckle machine having my invention incorporated therein;

FIG. 2 is another view similar to that of FIG. 1 but showing the parts in another position or sequence of operation;

FIG. 3 is a top plan view of the thread gripper mechanism shown in the right hand comer of FIG. 2;

FIG. 4 is a left side view of the machanism shown in FIG. 3;

FIG. 5 is a right side view of the mechanism shown in FIG. 3;

FIG. 6 is a side view of the mechanism shown in FIG. 3 when viewed from along the line 6-6 of FIG. 3;

FIG. 7 is a sectional view taken along the section line 7-7 of FIG. 4; and 1 FIG. 8 is an enlarged view of the thread gripper finger mechanism.

Referring now first to FIG. 1, shown therein is a portion of the I-Iinckle machine comprising a rear chuck l0 and a front chuck 11. They oscillate towards and away from each other about an axis 12 to transfer a curved needle 13 back and forth therebetween. The sewing head parts 10-13 are carried by a hanger 14 which is raised and lowered at the proper time. Only those parts will be shown and described which are necessary for an understanding of my invention. For a further description of the machine the reader is referred to said mentioned c opending United-States Hinckle patent application. I

Briefly, the lower back end of 1 the needle 13 is gripped by the chuck 10. Chuck 10 moves the upper front pointed end of the needle through a node 15 of formed work material into the front chuck 11. Front chuck l1 grips the front end of the needle and the rear chuck loreleases the needle. The front chuck continues to carry the needle clear through the node 15. After this the front chuck 11 backs up slightly to slacken the two strands of thread extending from the needle eye to the formed stitch. The rear strand of thread is a far loop 16 of thread and the front strand of thread is a near loop 17 of thread. After slackened loops 16 and'17 are formed by slight backing up of chuck 11 a looper arm 18 swings from the right to the left to enlarge the near loop 17 and transfer it to a thread puller mechanism indicated generally byreference numeral 19, see FIG. 2. The puller mechanism 19 comprises a finger 20 which picks up the enlarged loop 17 and transfers it to a not shown drum in mechanism 19 so that the trailing end of loop 17 which extends through the stitchis drawn entirely therethrough.

It will be appreciated that as the looper 18 picks up the near loop 17 and enlarges it into the size of FIG. 2 considerable force is exerted on the thread. This force is carried by the thread through the needle eye and far loop 16 back into the just formed stitch. If this is permitted puckering will occur in the stitched seam. Therefore, in my invention before the looper 18 picks up the near loop 17 a far loop thread gripper mechanism indicated generally by reference numeral 21 in FIGS. 1 and 2 comes into play. In FIG. 1 mechanism 21 is shown as having gripped the rear strand or far loop 16 before the looper 18 picks up the front strand or near loop 17,. In addition, the movement of the mechanism is so sequenced that after it grips strand 16 it will back up or withdraw slightly so that the part of the rear strand extending between the gripper 21 and the stitch has its slack taken up so that a near and compact stitch is formed.

After the gripper 21 grip holds the strand 16 and backs up slightly to take up the slack in the inner part of strand 16 the looper arm 18 picks up near loop 17 to enlarge it. Since at this time the grippers 21 hold the strand 16 the tension of the looper 18 'on the thread is not carried back into the just formed stitch. In FIG. 2 the loop 17 is shown in full enlarged position. By this time another thread gripper mechanism 22 grips the thread, it is hooked into a hook 20' and finger 20 is coming around to transfer the thread to the thread puller 19. Since the gripper 22, which is part of the original Hinckle machine, is now firmly holding the thread the pull of the looper 18, the finger 20 or the puller 19 on the thread will not be transmitted back through the needle eye into the formed stitch. Therefore, once the gripper 22 has the thread the grippers 21 release the thread, which is the position of the parts or operational sequence illustrated in FIG. 2.

The thread gripper mechanism 21 of my invention will now be described in detail in connection with FIGS. 3-8. In view of the fact that may thread gripper 21 comes into play before the thread gripper 22 of the basic Hinckle machine I shall denominate my thread gripper 21 the first thread gripper and the Hinckle thread gripper 22 the second thread gripper.

The first thread gripper comprises a pair of opposed crisscrossed fingers 23 and 23'. They are moved in and out and opened and closed by an operating mechanism mounted in a frame 24. A driven shaft 66 (see FIG. 3) extends lengthwise of the frame 24. Frame 24 is generally L-shaped and the shaft 66 has a rotary axis 32, see FIG. 4. Reference numerals 32 and 66 are also used in the Hinckle patent application to designate the same parts so that the placement of the first gripper operating mechanism can be readily oriented in the tool machine. Shaft 66 is the main drive shaft of the machine which carries several cams or the like for operating the various parts of the total machine in proper sequence or synchronism. A pair of cams 25 and 26 are mounted on shaft 66 to rotate therewith to also operate my first gripper mechansim.

One side of the frame 24 has a pair of bracket arms 27 and 28. One end of a pair of levers 29 and are pivoted on the outer end of brackets 27 and 28 respectively. Lever 29 extends-below the hub 25' of cam 25 and lever 30 extends above the hub 26' of cam 26. Each of levers 29 and 30 have cam followers 31 connected to their central portions. The follower 31 of lever 29 follows a cam track 33' of cam 25, see FIG. 4; and the follower 31 of lever 30 follows the cam track 33 of cam 26, see FIG. 5. i

The lever 29 is operated by cam 25 to open and close the gripper fingers 23 and 23 at the proper time. This is accomplished by pivotally connecting the other or free end of lever 29 to a slide 34. Slide 34 is vertically disposed and is guided up and down by guideway 35 formed in the frame 24. At its lower end the slide 34 has a guide slot 36. A bell crank lever 37 is positioned ahead of the slide 34. The bell crank lever 37 is pivoted at its center in a pair of spaced brackets 38 formed on a member 39, to be described hereinafter. The rear arm of bell'crank 37 has a roller 40 thereon which is disposed in the slot 36, see FIG. 7. The other arm of bell crank lever 37 extends through a slot 41 formed in member 39 for pivotal connection with the rear end of an elongated subassembly 42 which is pivotally connected at its forward end to the free end of gripper finger 23. By viewing FIG. 7 it will be readily seen that when lever 29 is caused to move by cam 25 the slide 34 is also caused to move. Since roller 40 follows slot 36 of slide 34, when slide 34 is moved to left or right when viewing FIG. 7 the bell crank lever 37 is pivoted to left or right respectively. Pivotal movement of bell crank lever 37 in turn causes subassembly 42 to move gripper finger 23 in one direction or the other to open and close the gripper fingers 23 and 23' in a manner to be described shortly.

The lever 30 is caused to move by the cam 26 to move the gripper fingers in and out or towards and away from the thread of the far loop 16. This is accomplished by pivotally connecting the other or free end of lever 30 to the upper end of a strut 43, see FIG. 7. The other or lower end of strut 43 is pivotally connected to another bell crank lever 44. The bell crank lever 44 is povited at its center to a fixed post 45 in the frame 24,

see FIG. 5. The rear arm of hell crank lever 44 is connected to the lower end of strut 43 and the other or forward arm of bell crank lever 44 is povitally connected to the rear end of member 39 by virtue of a pin 46 extending through a pair of spaced brackets 47 and the forward arm of bell crank lever 44. The brackets 47 comprise integral elements of the member 39.

The member 39 is elongated and extends lengthwise of frame 24 parallel to shaft 66 or its axis 32. It is actually a slide for moving the subassembly 42 and gripper far loop 16. The slide member 39 is guided on an L- shaped slide guide 48 mounted on the frame 24. The

slide guide 48 has a slot 49. A clamp plate 50 is provided for retaining slide member 39 on slide guide 48. Clamp plate 50 has a guide block 51 which is operative in slot 49, see FIG. 3.

v The gripper fingers 23, 23' as well as the subassembly 42 for opening and closing the same are mounted on the slide member 39 so they actually move therewith. At its inner end the subassembly 42 is connected'to slide member 39 by virtue of its connection with bell crank lever 37 which is mounted on brackets 38 of slide 39. The forward end of slide 39 had a lateral generally Z-shaped extension 52, see FIG. 4. The fingers 23, 23' are mounted on this extension 52 of slide 39. By referring also to FIG. 8 it will be seen that extension 52 is provided with two pins 53 and 54. The inner end of grip finger 23' is pivoted on pin 53. The center of grip finger 23 is pivotally mounted on pin 54. By referring to FIGS.

, 2 and 4 it will be seen that the right hand inner extremity of grip finger 23 is pivotally connected to the forward or outer end of subassembly 42. Gears 53 and 54' are rotatable about the pins 53 and 54 respectively. These gears 53 and 54' are connected to the grip fingers 23 and 23 respectively. When subassembly 42 moves it moves the grip finger 23. However, since the gears 53', 54 are in mesh movement of one finger 23 causes corresponding movement of the other grip finger 23. In this manner the grip fingers 23, 23' are opened and closed with respect to each other. The fingers 23, 23' are mounted on the pins 53, 54between the outer end 52 of slide 39 and a plate 55, see FIG. 4.

In the position of the parts illustrated in FIGS. 3-7 the slide 39 has been moved to its forwardmost position and the gripper fingers have been closed on the thread strand or far loop 16, see also FIG. 1. Referring to FIG. 7, this has been accomplished by the strut 43 moving to the right. When the bell crank lever 44 rotates to the right or clockwise when viewing FIG. 7, the slide 39 is caused to move forward carrying the subassernbly 42 and gripper fingers 23, 23' with it. When the strut 43 is moved to the right to move the gripper fingers to the thread strand 16 the gripper fingers are closed thereon by the lever 29 moving the slide 34 to the right when viewing FIG. 7. When slide 34 moves to the right bell crank lever 37 moves to the right or clockwise when viewing FIG. 7. When bell crank lever 37 moves clockwise the subassembly 42 is moved to the rear. Rearward movement of subassernbly 42 causes counterclockwise movement of the gripper finger 23 which is in a closing direction with respect to gripper finger 23'. Because of the meshed gears 53', 54' counterclockwise movement of gripper finger 23 results in clockwise movement of gripper finger 23' which is in a closing direction with respect to gripper finger 23. The cam tracks 33 and 33' of the cams 25 and 26 respectively are contoured to accomplish this sequence of operation at the proper moment of each stitch or cycle performed by the stitching machine. The gripper fingers 23, 23

release the thread strand 16 after the enlarged near loop 17 is gripped by the second gripper 22. After gripper fingers 23, 23' are opened they remain in open position and are retracted by slide 39. When the next stitch is madethe slide 39 moves the open gripper fingers 23, 23 forward, and then they close on the strand 16. After they close'on strand 16 slide 39 backs up slightly to take up the slack in strand 16. Afterthe grip per 22 grasps the near loop 17 the gripper fingers 23, 23' are again opened and withdrawn.

The strut 43 is joined at its opposite ends to the levers 30 and 44, and the subassernbly 42 to the lever 37 and the actuating arm extension of gripper finger 23, by ball socket type connections. These ball socket type connections are illustrated in the drawings and are understood by those skilled in the art. In addition, the subassernbly 42 actually comprises a forward and rear part having a spring connection therebetween. By viewing FIGS. 6 and 7 it will be seen that the rear and forward parts of subassernbly 42 have a pin 56 and slot 57 connection therebetween. When the subassernbly, 42 is moved to the rear to close the firwt gripper 21 if any overtravel occurs this will not be transmitted to the griper fingers 23, 23. Rather, the overtravel will be taken up by rearward movement of the pin 56 in the slot 57 and compression of a spring 58 on the subassernbly 42 in a manner which will be understood by those skilled in the art. This provision for overtravel as well as the ball socket type connections are for the purpose of obtaining a smooth running apparatus having no liklihood of jamming or malfunctioning while still staying within practical limits of manufacturing con trols and costs.

In view of the foregoing it will now be seen that my invention provides an improvement in the type of stitching machine disclosed in the mentioned Hinckle patent application which provides a stitch which is neat and compact without any puckering. This is obtained by the first gripper gripping the far loop of slackened thread and first backing up slightly to take up the slack therein to give a neat and compact stitch. This is a feature that can be controlled by using a properly contoured cam track 33. In addition, this is a feature which can be adjusted by changing the cam 26. Puckering is avoided by the first gripper 21 holding the thread 16 before the looper 18 comes into play anduntil after the second gripper 22 comes into operation. This is also a feature of the machine that can be controlled by the contour of cam track 33, and adjustments can be made by changing the cam 25.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention, and that it is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim: l V 1. In a stitching machine having a curved needle which is passed through work material and means for pulling the trailing end of the needle thread through the work material, means for preventing the tension on said trailing thread end exerted by said pulling means from being transmitted back into the stitch, which comprises:

a pair of opposed thread gripper fingers for grip holding the seam side of said thread prior to operation of said pulling means on said. trailing thread end,

means for moving said fingers towards and away from said seam side of said thread, and means for opening and closing said fingers, which includes:

a rotary cam track, a pivoted lever having a cam followerthereon operative in said cam track, and a slide connected to said lever, one slide having said fingers mounted thereon for moving the same towards and away from said seam side of said thread, and the other slide being operatively connected with said fingers for opening and closing the same,

said slides being movable in directions which are perpendicular to each other, the moving means lever being connected to its slide by a bell crank lever, and the other slide connection with said fingers comprising another bell crank lever, said another bell crank lever having a roller mounted on one of its arms, said roller being operative in a slot which is formed in said other slide parallel to the direction of movement of said moving means slide, and the other arm of said another bell crank lever extending transverse to the direction of movement of said moving means slide, a slot formed in the moving. means slide, and said another arm extending through said moving 

1. In a stitching machine having a curved needle which is passed through work material and means for pulling the trailing end of the needle thread through the work material, means for preventing the tension on said trailing thread end exerted by said pulling means from being transmitted back into the stitch, which comprises: a pair of opposed thread gripper fingers for grip holding the seam side of said thread prior to operation of said pulling means on said trailing thread end, means for moving said fingers towards and away from said seam side of said thread, and means for opening and closing said fingers, which includes: a rotary cam track, a pivoted lEver having a cam follower thereon operative in said cam track, and a slide connected to said lever, one slide having said fingers mounted thereon for moving the same towards and away from said seam side of said thread, and the other slide being operatively connected with said fingers for opening and closing the same, said slides being movable in directions which are perpendicular to each other, the moving means lever being connected to its slide by a bell crank lever, and the other slide connection with said fingers comprising another bell crank lever, said another bell crank lever having a roller mounted on one of its arms, said roller being operative in a slot which is formed in said other slide parallel to the direction of movement of said moving means slide, and the other arm of said another bell crank lever extending transverse to the direction of movement of said moving means slide, a slot formed in the moving means slide, and said another arm extending through said moving means slide slot. 